Multi-disc servo track writer vibration isolation method and apparatus

ABSTRACT

An actuator assembly and method for orienting a head over a disc within a multi-disc servo-track writer incorporates an actuator block, rotational air bearing, translational air bearing, adaptor plate, E-block and actuator arm/head assembly. Rotation of the E-block, and hence actuator arm/head assembly, is directly controlled by the movement of the rotational air bearing, which is rotated by a motor. The air bearing provides for reduced friction and, as a result, decreased eccentricity of the head as compared to related art configurations. A translational air bearing laterally positions the actuator assembly within the multi-disc servo-track writer for servo-track recording.

RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent applicationSer. No. 10/039,011, filed on Jan. 2, 2002, which claims priority ofU.S. Provisional Application Serial No. 60/295,275, filed Jun. 1, 2001.

FIELD OF THE INVENTION

[0002] This application relates generally to magnetic disc drives andmore particularly to an actuator assembly having a gas bearing foraccurately positioning transducers during servo-pattern recording.

BACKGROUND OF THE INVENTION

[0003] Disc drives are data storage devices that store digital data inmagnetic form on a rotating storage medium on a disc. Modem disc drivescomprise one or more rigid discs that are coated with a magnetizablemedium and mounted on the hub of a spindle motor for rotation at aconstant high speed. Information is stored on the discs in a pluralityof concentric circular tracks typically by an array of transducers(“heads”) mounted to a radial actuator or actuator arm for movement ofthe heads relative to the discs. Transducers are used to transfer databetween a desired track and an external environment. During a writeoperation, sequential data is written onto the disc track and during aread operation, the head senses the data previously written onto thedisc track and transfers the information to the external environment.Important to both of these operations is the accurate and efficientpositioning of the head relative to the center of the desired track.Head positioning within a desired track is dependent on head-positioningservo-patterns, i.e., a pattern of data bits used to maintain optimumtrack spacing and sector timing. Servo-patterns can be recorded betweenthe data sectors on each track of a disc, termed embedded servo, or onone dedicated surface of a disc within the disc drive, termed dedicatedservo.

[0004] Servo-patterns are typically recorded on a target disc during themanufacturing of the disc drive, by a servo-track writer (STW) assembly.There are basically two conventional methods for recording servo-patternonto a disc for use in a disc drive. In one method, an STW assembly isattached to a disc drive having a disc pack and read/write heads mountedin their proper positions. The mounted disc on the disc pack has notbeen pre-recorded with servo-pattern. The STW assembly attaches to theassembled disc drive and, using the actual drive's read/write heads,records the requisite servo-pattern directly to the mounted disc.Alternatively, and potentially more cost effectively, servo-pattern canbe recorded onto a plurality of disc prior to the discs being mountedinto a disc drive assembly. In this method, a multi-disc servo-trackwriter, having dedicated read/write heads or servo-recording headsrecords the servo-pattern onto each disc. One or more discs aresimultaneously prepared within the dedicated apparatus, allowing for thehigh throughput output of servo ready discs. The prerecorded discs arethen assembled into the drives.

[0005] Recent efforts within the disc drive industry have focused ondeveloping cost effective disc drives capable of storing more data ontoexisting or smaller sized disc surfaces. One potential way of increasingdata storage on a disc surface is to increase the recording density ofthe disc surface by increasing the track density (tracks per millimeter(tpmm)). Increased track density requires more closely spaced, narrowtracks, which in turn requires increased accuracy in recordingservo-pattern onto the target disc surface. This increased accuracyrequires that servo-track recording be accomplished within the increasedtolerances, but remain cost effective.

[0006] Dedicated multi-disc servo-track writers have traditionallyutilized servo-recording heads that are positioned on a target discsurfaces by pivoting and rotation in a radial path across the disc. Therotation of each head is typically accomplished by pivoting of anE-block within the writer, where the E-block rotates on ball bearings.Ball bearings, although effective for some existing devices, havelimitations as to how precisely the servo-recording head can be positionon a disc surface. For example, ball bearings often suffer from lobing,due to imperfections in the roundness of the ball bearings or smoothnessof the races, which results in unwanted vibration in the servo-recordingheads during servo-track recording. In addition, ball bearings sufferfrom a fair level of eccentricity, thereby adding a level of uncertaintyas to the exact rotational movement and position of the servo-recordingheads in relation to the axis of rotation. These imperfections in themanner in which the servo-recording heads are position result in anunacceptable level of accuracy, especially in light of the trend towardhigher track density, cost effective, discs.

[0007] There has been a long felt but unrecognized need, in high densityservo-track writing, for a mechanism to orient servo-recording heads ina substantially vibration-free manner, simultaneously maintaining a loweccentricity in their movements. Such a mechanism would allow for moreaccurate and cost effective recording of servo-patterns to disc surfacesand thereby allow for increases in disc track densities beyond presenttechnology limitations. Against this backdrop the present invention hasbeen developed.

SUMMARY OF THE INVENTION

[0008] Embodiments of the present invention include an apparatus andmethod for reducing eccentricity in a rotary actuator positioning aread/write head over a disc within a multi-disc servo-track writer(MDW). One embodiment of the present invention is a multi-disc trackwriter for recording information on one or more data storage discs. Thewriter may include an actuator assembly with an actuator block having acavity therein and a rotational gas bearing housed within the cavity forsupporting an E-block having one or more elongated actuator arms eachcarrying a data transducer.

[0009] The actuator assembly preferably has a translational gas bearingformed on a bottom face of the actuator block operable when moving theactuator assembly over a platform surface between a firstservo-recording position and a second disc loading and unloadingposition. A slide mechanism can be used for laterally moving theactuator block on a gas cushion provided by the translational gasbearing between the first and second positions. The actuator assemblyrotational gas bearing can have a rotatable spindle and an adaptor platefastened between the rotatable spindle of the rotational gas bearing andan E-block assembly carrying the transducers.

[0010] Another embodiment of the present invention is a method forpositioning a servo-recording head over a disc in a multi-disc trackwriter. The method includes the steps of:

[0011] (a) applying gas pressure to a translational gas bearing on abottom face of the actuator block to provide a float between theactuator assembly and the platform;

[0012] (b) laterally moving the actuator assembly on the translationalgas bearing to a servo-recording position;

[0013] (c) removing the gas pressure from the translational gas bearing;

[0014] (d) pulling a vacuum on the translational gas bearing toimmobilize the actuator assembly against the platform surface in theservo-recording position;

[0015] (e) applying gas pressure to a rotational gas bearing in theactuator block, the rotational gas bearing supporting theservo-recording head; and

[0016] (f) rotating the servo-recording head on the rotational gasbearing.

[0017] These and various other features as well as advantages whichcharacterize the present invention will be apparent from a reading ofthe following detailed description and a review of the associateddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a plan view of a disc drive having a disc prepared usingan embodiment of the present invention.

[0019]FIG. 2 is a schematic plan view of a multi-disc servo-track writer(MDW) incorporating an actuator assembly in accordance with anembodiment of the present invention.

[0020]FIG. 3 is a perspective view of the MDW in FIG. 2.

[0021]FIG. 4 is a separate perspective exploded actuator end view of theactuator assembly in FIG. 2 in accordance with one embodiment of thepresent invention.

[0022]FIG. 5 is a perspective exploded rear view of the actuatorassembly shown in FIG. 3.

[0023]FIG. 6 is a bottom view of the actuator assembly shown in FIG. 4.

[0024]FIG. 7 is an enlarged cross-sectional view through the actuatorblock taken along line 5-5 in FIG. 6.

[0025]FIG. 8 is a close-up perspective view of the MDW above in FIG. 2with disc pack on the spindle motor hub with the spindle motor removedin accordance with a preferred embodiment of the present invention.

[0026]FIG. 9 is a process flow diagram of the steps for servo writing adisc pack in a servo-track writer in accordance with one embodiment ofthe present invention.

DETAILED DESCRIPTION

[0027] A disc drive 100 having a disc manufactured in accordance withthe present invention is shown in FIG. 1. The disc drive 100 includes abase 102 to which various components of the disc drive 100 are mounted.A top cover 104, shown partially cut away, cooperates with the base 102to form an internal, sealed environment for the disc drive 100 in aconventional manner. The components include a spindle motor 106 thatrotates one or more discs 108 at a constant high speed. Information iswritten to and read from tracks, as illustrated by broken line 109, onthe discs 108 through the use of an actuator assembly 110, which rotatesabout a bearing shaft assembly 112 positioned adjacent the discs 108.The actuator assembly 110 includes a plurality of actuator arms 114which extend towards the discs 108, with one or more flexures 116extending from each of the actuator arms 114. Mounted at the distal endof the flexures 116 is a head 118 that includes an air bearing slider(not shown) enabling the head 118 to fly in close proximity above thecorresponding surface of the associated disc 108. The head 118 includesa writing element, i.e., write head, to record information to the disc108 and a reading element, i.e., read head, to transfer data from thedisc 108 to the host computer (not shown).

[0028] The radial positioning of the heads 118 is controlled through theuse of a voice coil motor 120, which typically includes a coil 122attached to the actuator assembly 110, as well as one or more permanentmagnets 124, which establish a magnetic field in which the coil 122 isimmersed. The controlled application of current to the coil 122 causes amagnetic interaction between the permanent magnets 124 and the coil 122so that the coil 122 moves in accordance with the well-known Lorentzrelationship. As the coil 122 moves, the actuator assembly 110 pivotsabout the bearing shaft assembly 112 and the heads 118 are caused tomove across the surfaces of the discs 108.

[0029] Proper orientation of the heads 118 over the disc surface reliesupon pre-recorded servo-patterns on the disc. The present inventionprovides a method for recording servo-pattern to a disc 108 as well asan actuator assembly 134 having a pair of air bearings (see below) forthe accurate positioning and movement of servo-recording heads duringservo-pattern recording on a disc. Typically, servo-pattern is recordedonto disc 108 during the manufacture of the disc drive 100. A dedicatedservo writing apparatus, termed a multi-disc servo-track writer 136, canbe used to record servo-pattern onto the disc surfaces. These discs arethen assembled into disc drives 100 during the manufacturing process ofa number of discs 108 simultaneously.

[0030] FIGS. 2-8 illustrate an actuator assembly 134 in a multi discservo-track writer 136 in accordance with an embodiment of the presentinvention. FIGS. 2 and 3 show one potential multi-disc servo-trackwriter 136 for use with the present invention. The multi-discservo-track writer 136 includes an actuator assembly 134 for moving theservo-recording heads 140 (see FIGS. 3 and 7) necessary for recordingservo-patterns onto a stack of target discs 108. A spindle hub assembly142 attached to a spindle motor 143 vertically positions one or moretarget discs 108 onto which the servo-pattern is to be recorded. Avacuum chuck 144 rigidly secures the actuator assembly 134 in a desiredposition for servo-track writing and fastens the spindle hub assembly tothe spindle motor 143. A laser transducer system 146 measures theangular displacement and consequent positioning of the servo-recordingheads 140 of the actuator assembly 134 for servo-pattern recording.These components of the multi-disc servo writer 136 are fastened to aflat, rigid base or platform 148. The platform 148 is preferably agranite slab, as is shown in FIG. 3.

[0031] The accuracy of the servo-pattern recorded on a disc surface 138relies upon, among other things, the vibration free positioning andmovement of the servo-recording heads 140 over target disc 108locations. Accurate positioning and vibration free movement of theservo-recording heads in turn depends upon the accurate movementpositioning of the actuator assembly 134 in relation to the target discs108 as well as the smooth, vibration free movements of the recordingheads 140 over the disc surface 138, i.e., the heads move with reducedvibration and eccentricity over a target disc surface as compared to theconventional movement of servo-recording heads. Embodiments of thepresent invention provide an actuator assembly 134 for use in amulti-disc servo-track writer 136, having a translational air bearing150 (see FIG. 4) for the lateral positioning of the actuator assembly134 within the multi-disc servo-track writer 136, and a rotational airbearing 152 (see FIG. 4) for the rotation of the servo-recording head(s)140 on the actuator assembly 134 over disc surfaces 138 within themulti-disc servo writer 136. The combination of air bearings 150 and 152provides the actuator assembly 134 with enhanced positional accuracy,and the servo-recording heads 140 with reduced vibrational noise andeccentricity during servo-track recording.

[0032] Continuing to refer to FIGS. 2 and 3, the multi-disc servo-trackwriter 136 is secured to a flat surface of a substantially immobileplatform 148. The actuator assembly 134 is connected to the platform 148via a slide mechanism 154 for lateral movement of the actuator assembly134, as indicated by arrow 156, over the platform 148 between aservo-recording position 158 and disc loading and un-loading position160. The actuator assembly 134 is shown in the disc unloading positionin FIG. 3. The actuator assembly 134 is shown in the servo-recordingposition 158 in FIGS. 2 and 8.

[0033] The spindle motor hub assembly 142 and vacuum chuck 144 are bothfastened to the platform 148. Note that the actuator assembly 134 andspindle hub assembly 142 are positioned in a head-to-head fashion forrotations about parallel horizontal axes. The spindle hub assembly 142vertically positions one or more discs 108 for the simultaneous writingof servo-pattern onto each disc 108 by servo-recording heads 140 locatedon the actuator assembly 134 (see FIGS. 3 and 8). The vacuum chuck 144is rigidly secured in proximity to the actuator assembly 134 to pull avacuum on the translational air bearing 150 of the actuator assembly 134and thereby secures the servo-recording position 158 or disc loading andunloading position 160.

[0034] In general, target discs 108 are assembled into a multiple discpack that is mounted to the spindle motor hub assembly 142 where theactuator assembly 134 is moved laterally into position 158 forservo-recording. Servo-recording heads 140 on the actuator assembly 134are rotated over the mounted disc surface 138 and servo-patternrecorded, the servo-recording heads 140 are rotated off of the discsurface 138, and the actuator assembly 134 moved laterally away from themounted disc for unloading and use in a disc drive 100.

[0035] An embodiment of the actuator assembly 134, in accordance withthe present invention, is shown in FIG. 4. The actuator assembly 134includes an actuator block 162 housing a rotational air bearing 152, atranslational air bearing 150, an E-block assembly 164 that includes anE-block 166, a series of one or more actuator arms 240 carryingrecording heads 140 thereon, a DC torque, brushless motor 168 (see FIG.2) or like motor 246 (see FIGS. 3 and 5) for actuating the rotationalair bearing 152, a sliding mechanism 154 for translational movement ofthe actuator block 162, and a laser transducer assembly 146 forcoordinating the motor's movement with the servo-recording head'sposition. In preferred embodiments, the actuator assembly 134 alsoincludes an adaptor plate 170 coupling the E-block assembly 164 to therotational air bearing 152, as described in greater detail below.

[0036] With continued reference to FIG. 4, the actuator block 162 of theactuator assembly 134 has a generally cube-like shape housing having acavity or chamber 172 for receiving the rotational air bearing 152 andassociated DC torque, brushless motor 168 therein. The actuator block162 defines two aligned circular-like openings, an opening 174 on thefront face of the actuator block that faces toward the spindle hub motorassembly and a second opening (not shown) on the opposite or back faceof the actuator block 162. The openings are of sufficient diameter toreceive the rotational air bearing 152 and DC torque brushless motor.(See 168 in FIG. 2 or 246 in FIG. 5).

[0037] The slide mechanism 154 is used, in coordination with thetranslational air bearing 150, to laterally move the actuator assembly134 over the base 148 toward and away from the spindle motor hubassembly 142. The slide mechanism 154 attaches to a lower edge 174 of aside face 176 of the actuator assembly 134, and preferably to a loweredge of the side face adjacent the vacuum chuck 144. The slide mechanism154 includes a pneumatically sliding cylinder 178 attached to theplatform 148 by a flexure or bracket 180. A pair of stops 182 extendalong the lower edge 174 of the side face 176 of the actuator block 162on opposite sides of the actuator block attached sliding mechanism. Eachstop 182 extends beyond the front face 184 and back face 186 of theactuator block 162. A pair of catch block 187 is positioned on theplatform 148 on opposite sides of the actuator block 162 to contact eachstop when the sliding mechanism 154 laterally moves the actuatorassembly 134 to the servo-recording position 158 on the platform.

[0038] The rotational air bearing 152 has an inner, freely rotatablespindle 188 contained within an outer, non-rotating race 190. Theinterface between the spindle 188 and outer race 190 provides a chamber(not shown) for receiving pressurized air, thereby creating asubstantially frictionless air float, allowing the substantiallyfrictionless rotation of the spindle 188 in relation to the outer race190. An air port 192 in the outer race 190 provides communicationbetween an external air source (not shown) and the chamber (not shown)formed between the spindle 188 and outer race 190. The air port 192extends outwardly from the outer race 190 and fits through an opening194 in the top surface 196 of the actuator block 162. One conventionalrotational air bearing that may be used in the present invention ismanufactured by Precision Instruments, Inc.

[0039] A doughnut shaped first clamp 198 having a central aperture 200fits on the front end 202 of the outer race 190 of the rotational airbearing 152 and receives the inner spindle 188 through its centralaperture 200. A series of semi-circular rings 204 extend from the outersurface of the first clamp 198 to align with bores 206 cut into thechamber wall 208 of the actuator block 162. A series of retaining holes210 are equidistantly placed around the clamp 198 to align with bores212 in the front end of the outer race of the rotational air bearing.Screws 214 or other like means are used to secure the first clamp 198 tothe front end 202 of the outer race 190 of the rotational air bearing152 utilizing the aligned bores 210 and 212. The outwardly extendingrings 204 on the first clamp 198 align with the bores 206 cut into thechamber wall of the actuator block. A second doughnut shaped clamp 216fits over the first clamp 198 having outwardly extending rings 218 thatalign over the rings 204 of the first clamp 198 and over thecorresponding bores 206 in the chamber wall of the actuator block 162.Bolts 220 or other means are threaded through the rings of the second218 and first 198 clamp thereby securing the rotational air bearing 152within the actuator block chamber 172, where the font end 222 of thespindle 188 extends to the circular opening in the actuator block'sfront face 184. It is envisioned that the rotational air bearing 152could be secured with the actuator block 162 in any number of ways, allof which are considered to be within the scope of the present invention.

[0040] The front face 222 of the spindle 188 of the rotational airbearing 152 defines a series of equidistantly spaced holes 224 whichreceive screws 226 or bolts used to secure the disc spaced adaptor plate170 onto the rotational spindle 188. The adaptor plate 170 is secured toand rotates with the rotational air bearing spindle 188. A threaded stud228 extends horizontally from the center of the adaptor plate, the stubaligned with the rotational air bearing axis of rotation, and receivesand secures an E-block assembly 164 (see below). Between the centrallylocated stud 228 and outer circumference 230 of the adaptor plate 170,an alignment pin 232 extends for facilitating the orientation of theE-block assembly 164 during installation on the adaptor plate 170. Inaddition, a corner cube 234, used to communicate the adaptor plate'sangular displacement, is held on the adaptor plate 170 through glue or aretainer/pin arrangement 236 as shown in FIG. 4.

[0041] As previously mentioned, the E-block assembly 164 is positionedon the stud 228 and alignment pin 232 located on the front face of theadaptor plate 170. An elongated bolt 238 attaches the E-block 164 to theadaptor plate 170 (see FIG. 7) so that actuator arms 240 extend in thevertical plane, or substantially perpendicular, to the rotational airbearing's axis of rotation, as indicated by line 242. Attached to thedistal end of each actuator arm 240 of the E-block is a load beamassembly or two facing load beam assemblies, having associatedservo-recording heads 140 thereon for servo-recording to the disc 108located on the spindle motor hub assembly 142 (see FIG. 8).

[0042]FIG. 5 illustrates a perspective exploded view of the rear face186 of the actuator block 162. A stator 244 of the DC torque, brushlessmotor 246 is glued adjacent the back end of the rotational air bearing152 within the chamber 172. The stator 244 controls the rotationalmovement of the spindle 188 of the rotational air bearing 152 inconjunction with a trigger plate 248 and optical switches 250 as is wellknown in the art.

[0043] In use, actuation of the motor 246 causes a correspondingrotational movement of the rotational air bearing 152 about its axis ofrotation 242, which causes the rotation of the E-block assembly 164about the rotational air bearing axis of rotation 242. The rotationalmovement of the E-block assembly 164 about the rotational air bearingaxis of rotation has a very small level of eccentricity and therebyprovides for extremely accurate servo-recording head 140 positioning.

[0044] In addition, rotation about the air bearing 152 results in muchlower levels of friction, especially as compared to conventional ballbearings, thereby providing for minimal levels of vibration duringpositioning of the servo-recording heads over the disc surfaces.

[0045] As shown in FIGS. 6 and 7, the bottom face 252 of the actuatorblock 162 defines a translational air bearing 150. The translational airbearing 150 includes a groove 254 that extends around the periphery ofthe bottom face 252 of the actuator assembly, having two or more equallyspaced air ports 256 for receiving pressurized air (not shown) into thegroove. A planar landing 258 is on either side of the groove 254, wherethe two planar landings 258 are substantially parallel to each other andto the top surface of the platform 148. The first landing 260 extendsfrom the groove 254 to the outer edge 262 of the bottom face 252 of theactuator assembly and the second landing 264 extends a uniform distancefrom the groove 254 until the start of a centrally located recess 266within the bottom face of the actuator assembly. A vacuum port 268 ispositioned within the recessed 266 bottom face of the actuator assembly.

[0046] The groove 254 in preferred embodiments of the present inventionis preferably from 0.005 to 0.050 inches deep and is more preferablyapproximately 0.015 inches deep. The centrally located recess 266 in thebottom face 252 of the actuator assembly is preferably from 0.002 to0.010 inches deep, and is more preferably approximately 0.005 inchesdeep. The shape of the groove 254 is preferably a square having roundedoff corners. In use, when the actuator block 162 needs to betranslationally moved over the platform 148, an air source (not shown)supplies pressurized air to the groove via ports 256. The pressurizedair raises the actuator block 162 off the platform 148 and issubstantially kept within both the grove 254 and within the recess 266thereby providing a float between the bottom face 252 of the actuatorblock and the top surface of the platform 148. When the actuator block162 needs to be secured in one of the desired positions on the platform,the pressurized air is removed and a vacuum applied to the bottom faceof the actuator block by pulling a vacuum through the vacuum port 268 bythe vacuum chuck 144. The co-planar landings 258 on either side of thegroove 254 provide a substantially air tight connection between theactuator block and the platform.

[0047]FIG. 9 is a process flow diagram showing the steps for positioningand rotating a servo-recording head in relation to a disc surfaceutilizing one embodiment of the present invention. In operation 500, adisc pack is loaded onto the multi-disc servo-track writer 136 forservo-track recording onto each disc 108. In operation 502, asatisfactory amount of air is applied to a translational air bearing inthe actuator assembly 134 to provide a float between the actuatorassembly 134 and the platform 148. In operation 504, a slide mechanism154 that connects the actuator assembly to the platform 148 is actuatedto laterally move the actuator assembly 134 into a servo-recordingposition. In operation 506, a vacuum chuck 144 pulls a vacuum on theactuator assembly 134 to secure the assembly in the requiredservo-recording position. In operation 508, a motor 168 is actuated torotate the rotational air bearing 152 for unloading the servo-recordingheads from a comb 169 and positioning the servo-recording heads 140 onthe disc surfaces 138. In operation 510, a servo-pattern is recorded oneach of the target disc surfaces. In operation 512, the servo-recordingheads 140 are removed from the disc surfaces 138 upon completion ofservo-pattern recording and stored back on the comb 169. In operation514, air pressure is added to the translational air bearing 150 tore-establish the float between the actuator assembly 134 and theplatform 148. In operation 516, the slide mechanism 154 laterally movesthe actuator assembly 134 to a non-servo-pattern recording position andthe disc stack is removed from the multi-disc servo-track writer 136. Inoperation 518, servo-recorded discs 108 are removed from the disc stackand installed into target disc drives such as disc drive 100.

[0048] In summary, an embodiment of the present invention may be viewedas an actuator assembly (such as 134) for use in a multi-disc trackwriter (such as 136) for recording information on one or more datastorage discs (such as 108) that includes an actuator block (such as162) having a central cavity therein (such as 172) and a rotational airbearing (such as 152) housed within the central cavity (such as 172) ofthe actuator block (such as 162) for supporting an E-block (such as 164)having one or more elongated actuator arms (such as 240) each carryingat a distal end thereof one or more transducers (such as 140) each forrecording the information on a disc surface.

[0049] The actuator assembly (such as 134) has a translational airbearing (such as 150) formed on a bottom face (such as 252) of theactuator block (such as 162) operable when moving the actuator assemblyover a platform surface (such as 148) between a first servo-recordingposition and a second disc loading and unloading position. A slidemechanism (such as 154) is used for laterally moving the actuator block(such as 162) on an air cushion provided by the translational airbearing (such as 150) between the first and second positions. Thetranslational air bearing has a groove (such as 254) juxtaposed betweentwo planar lands (such as 260 and 264) on the actuator block bottom face(such as 252) that extend around a centrally located recess (such as266) in the bottom face (such as 252) of the actuator block (such as162).

[0050] The actuator assembly (such as 134) rotational air bearing (suchas 152) has a rotatable spindle (such as 188) and an adaptor plate (suchas 170) fastened between the rotatable spindle (such as 188) of therotational air bearing (such as 152). The adapter plate (such as 170)supports the E-block (such as 164). The rotational air bearing has anaxis of rotation substantially parallel to the surface of the platform(such as 148). The actuator assembly (such as 134) has one or moreelongated actuator arms (such as 242) oriented substantiallyperpendicular to the rotational air bearing axis of rotation and has amotor (such as 246) coupled to the rotational air bearing spindle (suchas 188). A corner cube (such as 234) participates in providingpositional information for controlling the motor (such as 246) toposition the E block (such as 164) carrying the transducers (such as140) over the disc surfaces. The actuator assembly also has a stop (suchas 182) positioned on the actuator block adjacent the platform surface(such as 148) and a catch block (such as 187) extending from theplatform (such as 148). The actuator assembly (such as 134), moving onthe translational air bearing (such as 150), is positioned in theservo-recording position when the stop (such as 182) interacts with thecatch (such as 187).

[0051] An embodiment of the present invention may alternatively beviewed as a method for positioning a servo-recording head (such as 118)over a disc (such as 108) in a multi-disc track writer (such as 136)wherein the servo-recording head (such as 140) is on an actuatorassembly (such as 134) coupled to a platform (such as 148) surface by anactuator block (such as 162) and the disc (such as 108) is on a spindlehub (such as 142) coupled to a spin motor (such as 143) fastened to theplatform surface. The method includes the steps of:

[0052] (a) applying gas pressure to a translational gas bearing (such as150) on a bottom face (such as 252) of the actuator block (such as 162)to provide a float between the actuator assembly (such as 134) and theplatform (such as 148);

[0053] (b) laterally moving the actuator assembly (such as 134) on thetranslational gas bearing (such as 150) to a servo-recording position(such as 158);

[0054] (c) removing the gas pressure from the translational gas bearing(such as 150);

[0055] (d) pulling a vacuum on the translational gas bearing (such as150) to immobilize the actuator assembly (such as 134) against theplatform surface in the servo-recording position (such as 158);

[0056] (e) applying gas pressure to a rotational gas bearing (such as152) in the actuator block (such as 162), the rotational gas bearingsupporting the servo-recording head (such as 140); and

[0057] (f) rotating the servo-recording head (such as 140) on therotational gas bearing (such as 152).

[0058] The translational gas bearing (such as 150) on the bottom surface(such as 252) of the actuator block (such as 162) has a groove (such as254) juxtaposed between two planar landings (such as 258) that receivespressurized gas and that extends around a centrally located recess (suchas 266) in the bottom face of the actuator block. The method further mayinclude steps of:

[0059] (g) recording information on the disc (such as 108);

[0060] (h) rotating the servo-recording head (such as 140) off of thedisc;

[0061] (i) removing the gas pressure from the rotational gas bearing(such as 152) in the actuator block (such as 162);

[0062] (j) applying gas pressure to the translational gas bearing (suchas 150); and

[0063] (k) moving the actuator block (such as 162) to a disc loading andunloading position (such as 160).

[0064] (l) removing the air pressure from the translational gas bearing(such as 150); and

[0065] (m) pulling a vacuum on the translational gas bearing toimmobilize the actuator assembly (such as 134) in the disc loading andunloading position (such as 160).

[0066] An embodiment of the present invention may also be viewed as anactuator assembly (such as 134) for recording information onto a discsurface in a multi-disc track writer (such as 136). The actuatorassembly (such as 134) includes an E-block (such as 166) having one ormore elongated actuator arms (such as 240), each actuator arm (such as240) having a distally located recording head (140); andvibration-isolation means for rotating the E-block (such as 166) in theactuator assembly (such as 134) to position the recording heads (such as140) over a disc (such as 108) surface. The vibration-isolating meansfor rotating the E-block is preferably a rotational air bearing (such as152). The air bearing (such as 152) has a rotatable spindle (such as188) fastened to the E-block assembly (such as 164). The actuatorassembly (such as 134) also has a means for moving the actuator betweena recording position (such as 158) and a disc loading and unloadingposition (such as 160). This means for moving the actuator includes atranslational air bearing (such as 150) and a slide mechanism (such as154) for moving the actuator assembly (such as 134) along a platform(such as 148) surface.

[0067] It will be clear that the present invention is well adapted toattain the ends and advantages mentioned as well as those inherenttherein. While a presently preferred embodiment has been described forpurposes of this disclosure, various changes and modifications may bemade which are well within the scope of the present invention. Numerousother changes may be made which will readily suggest themselves to thoseskilled in the art and which are encompassed in the spirit of theinvention disclosed and as defined in the appended claims.

What is claimed is:
 1. A track writing apparatus comprising: a base; anactuator block having a central cavity therein; a rotational bearingwithin the central cavity of the actuator block for supporting anE-block having at least one actuator arm carrying at least onetransducer for recording information on a data storage disc; and atranslational gas bearing operable to move the actuator block between afirst position on the base and a second position on the base.
 2. Thetrack writing apparatus of claim 1 wherein the translational gas bearingincludes a groove formed in a face of the actuator block, abutting asurface of the base.
 3. The track writing apparatus of claim 2 furthercomprising a slide mechanism coupled between the base and the actuatorblock for moving the actuator block on the translational gas bearingbetween the first and second positions.
 4. The track writing apparatusof claim 2 wherein the first position is a servo-recording positionadjacent the data storage discs and the second disc position is spacedfor loading and unloading data storage discs.
 5. The track writingapparatus of claim 2 wherein the groove is continuous.
 6. The trackwriting apparatus of claim 1 wherein the gas bearing has a rotatablespindle carrying an adaptor plate supporting the E-block.
 7. The trackwriting apparatus of claim 6 further comprising a motor coupled to therotatable spindle for positioning the transducer.
 8. The track writingapparatus of claim 7 further comprising a corner cube couple to theadaptor plate to provide angular positional information of the E-block.9. The track writing apparatus of claim 2 further comprising a stroppositioned on the actuator block adjacent the surface and a catchsupported by the platform, wherein the stop interacts with the catch tolimit movement of the actuator assembly.
 10. An actuator assembly forrecording information onto a disc surface in a multi-disc track writer,the actuator assembly comprising: an E-block having one or moreelongated actuator arms, each actuator arm having a distally locatedrecording head; and a stationary vibrationless means for rotating theE-block in the actuator assembly to position the recording heads over adisc surface.
 11. The actuator assembly of claim 10 wherein thevibrationless means for rotating the E-block is a rotational gasbearing.
 12. The actuator assembly of claim 10 wherein the gas bearinghas a rotatable spindle fastened to the E-block.
 13. The actuatorassembly of claim 10 further comprising means for moving the actuatorbetween a recording position and a disc loading and unloading position.14. The actuator assembly of claim 13 wherein the means for moving theactuator includes a translational gas bearing.
 15. The actuator assemblyof claim 14 wherein the means for moving further includes a slidemechanism for moving the actuator assembly along a platform surface.